In one of my PCs I swapped out an Athlon II X2 CPU for a Phenom II X4. All other hardware remains unchanged. Then I noticed that FB DOS programs are no longer working. A very simple "hello world" program will run but when using graphics SCREEN it fails at some point...

There is a newer CWSDPMI, one from 2000 and one from 2010. I tried those, with no change. I also tried disabling CPU cache in the BIOS (again, no change).

Then I put the other CPU back in and things work again. However, there are still some GPFs when moving the mouse. Without the mouse driver being loaded there are no problems. I suspect the mouse driver may have been the problem. (But I'm not inclined to swap CPUs again at the moment to confirm.)

Hm, interresting. Does the Phenom II X4 integrate some chipset functionality (like in southbridge/northbridge circuits) just on the chip itself? Because it sound like some kind of A20 gate problem.You should more experiment with various memory setups. By the way - does it occur if you run your samples from running Win98?

DamageX wrote:Then I put the other CPU back in and things work again. However, there are still some GPFs when moving the mouse. Without the mouse driver being loaded there are no problems. I suspect the mouse driver may have been the problem. (But I'm not inclined to swap CPUs again at the moment to confirm.)

According to Wikipedia, it was the original Phenom that had a TLB bug, so my first hunch was wrong here.

I was using MouseWare 6.30 that I've had since ancient times. I tried CTMOUSE and that resulted in crashes as well. I guess the real problem is the PS/2 mouse emulation in the BIOS (the system has a USB mouse). I tried disconnecting the USB mouse and connecting a serial mouse instead and then FB programs ran fine with either driver.